In the prior art, it is well known to use alcohol fuel in modified engines for such applications as drag racing, tractor pulling or the like. Typically, these alcohol fuel systems employ an on/off valve which provides fuel from a fuel pump at maximum pressure to fuel injectors or the like.
Referring now to FIG. 1, a typical prior art alcohol fuel system is generally designated by the reference numeral 10 and includes a fuel tank 1, fuel pump 3, on/off valve 5, fuel injection system 7 and engine 9. Other conventional components such as fuel filters and fuel injection metering valves are not shown for clarity purposes.
The fuel system 10 also includes recycle or recirculating lines 11 which recirculate fuel back to the tank 1 which is not used in the engine 9. Since the on/off valve 5 is either fully open or fully closed, the amount of fuel in the recirculating lines 11 controls the fuel input to the engine 9. That is, if the fuel rate is high in recirculating lines 11, the fuel mixture to the engine will be lean. Likewise, if the recirculating fuel flow is low, the fuel mixture to the engine will be rich.
One of the problems with these types of fuel systems is fuel aeration in the fuel tank. Since the fuel is recirculated to the fuel tank, the fuel therein becomes agitated and air bubbles are entrained therein. This aerated fuel mixture, necessarily having a lower BTU or fuel value, is then fed to the fuel injection system. The lower fuel value results in poorer engine performance.
Recirculating the fuel back to the fuel tank is also costly since long runs of the recirculating fuel lines are needed. The lines being made of braided stainless steel surrounding a high pressure rubber hose. Moreover, since modern fuel injection systems use three or four fuel injectors, each injector having its own recirculating line 11, a large quantity of hose is required for recirculation.
The prior art fuel system is also disadvantageous in that the on/off valve can slip out of the fully on position and starve the fuel injection system and engine of necessary fuel.
In view of the disadvantages noted above, a need has developed for an improved alcohol-based fuel system. In response to this need, the present invention provides a unique fuel shut-off valve which eliminates the need for extensive lengths of recirculating hose line, aerated fuel and improperly functioning on/off valves. The present invention provides a fuel shut-off valve which recirculates unused fuel from both the fuel pump and fuel injection system directly to the fuel pump rather than the fuel tank. The inventive valve also includes a positive locking mechanism to maintain the valve in its on or off position.